When 'Hawkman' moved from the Golden Age of Comics to the Silver Age, it brought with it a peculiarity of the science-fiction/fantasy genre. Actually, "peculiarity" is an unfair term; a better phrase would be, "additional design complication." Because when editor Julius Schwartz updated Hawkman, he changed him from a reincarnated Egyptian prince to a policeman from the alien planet of Thanagar (reboots being a bit...bolder...in those days), he and writer Gardner Fox needed to pay more attention than usual to the setting of the comic. After all, it wasn't just "Midway City" they were setting up as the usual home of Hawkman's adventures. They also had to set up the planet of Thanagar.
The concept of "world-building", setting up an internally consistent alien setting with a history, culture, and geography separate from the planet Earth, is one aspect of designing a storytelling engine that hasn't been left to chance. Many science-fiction writers have discussed ways of going about world-building, and it's considered to be an essential element of the craft in both the sci-fi and fantasy genres. Perhaps, at times, people have paid a bit too much attention to it--many fantasy novels seem to be more excuses to show off the world-building by crafting a plot than coming up with a plot and finding a world for it to take place in. However, it is at least one area where writers have some resources to guide them.
How does Hawkman's world work? A bit haphazardly; as with many comics of the Silver Age, the primary focus was on coming up with quick, pacy kid-friendly stories, and things like "continuity" took a backseat. But it does hang together; the Thanagarian society was peaceful and technologically advanced, but had no cultural concept of "theft". Alien raiders called 'Manhawks' arrived to plunder the planet, and Thanagarians formed their first police forces, the Hawkmen, to repel them. The damage had been done, though; once the concept of theft had been introduced to the culture, Thanagarians began stealing things for fun. The Hawkmen had to learn how to be policemen, not simply a militia, and sent Katar Hol and his wife Shayera to Earth to learn our techniques. (This, of course, explains the sudden 1,000,000% increase in police brutality on Thanagar.)
Obviously, this isn't Tolkein (although the notion of a society without a concept of "theft" isn't as far-fetched as it sounds.) But in this particular case, it doesn't have to be, because Thanagar is a background setting for Hawkman's adventures on Earth. Other, more overtly science-fiction comics, like 'Guardians of the Galaxy' or 'Adam Strange', worked a bit harder at building a world for their characters to inhabit, and in the wake of 'Crisis on Infinite Earths', even Thanagar got a makeover in keeping with the increased emphasis on world-building in genre fiction.
The main point is that adding in a science-fiction/fantasy world does mean extra work for a writer, at least in the initial design stages. Fox didn't need to flesh out Midway City too much, because human beings are generally familiar with big cities, and can let our minds fill in the details that Fox didn't bother with. (And let's face it, Midway City was just Chicago with the serial numbers filed off.) But when you have an alien world, you have to work out all of the major elements yourself, because the reader isn't going to do nearly as much of the work for you.
The pay-off, though, is that once you've done that initial design work, you have a number of additional story elements that will keep generating ideas for you. Thanagar's setting becomes a new story generator, and with any storytelling engine, the more story generators you have, the better.